1. Field of the Invention
The present invention relates to connection pin assemblies for attaching replaceable implements to earthworking buckets of excavating equipment and the like. The invention also relates to a method of attachment, and to earthworking buckets with replaceable implements attached by means of the connection pin assemblies.
2. State of the Art
Earth working buckets used for heavy earthworks applications such as mining are fitted with teeth for engaging the ground surface. Due to the highly abrasive nature of the materials encountered by the teeth, they wear more quickly than the bucket. For this reason, they are detachably connected to the bucket to allow replacement.
On smaller buckets, the teeth are generally attached directly to an adaptor on the bucket by means of a connection pin. On larger buckets, intermediate adaptors are attached to the bucket nose and the teeth are attached to respective of the intermediate adaptors. Both connections are by means of connection pins, so that the teeth and intermediate adaptors can be replaced as required.
Connection pin assemblies of the type generally employed, and with which this invention is concerned, are known in the art as spool and wedge (or clamp and wedge) assemblies.
Prior art spool and wedge assemblies include a spool, often C-shaped with tapered engagement surfaces, which can be inserted into aligned apertures in the parts to be connected. A wedge is then inserted to contact the rear surface of the C and is driven home by sledgehammer to cause lateral expansion of the spool and wedge until it bears firmly against appropriate parts of the inner walls of the apertures to provide lateral loading and optionally a clamping action of the adaptor in the case of `Whisler` style attachments. Any part of the spool and wedge protruding above or below the aligned apertures is then cut off by oxy acetylene equipment.
The tightness of the connections must be regularly monitored, and when a tooth or intermediate adaptor works loose the spool and wedge must be tightened by hammering the wedge in further. This can be difficult as the protruding part of the wedge may already have been removed and thus the end of the wedge is not readily accessible. When the tooth or intermediate adaptor requires replacement, the spool and wedge often has to be cut out.
It will be appreciated that the fitting, monitoring, adjustment and removal of the prior art spool and wedge assemblies is time consuming and labour intensive, particularly as each bucket will have a number of teeth and an equal number of adaptors, each attached by respective spool and wedge assemblies.
Patent Application No. PCT/AU94/00035 describes a spool and wedge assembly in which a pair of spools are forced apart by a pair of wedges which are drawn together by a bolt. While that disclosure is in some respects an improvement over the prior art, it leaves much scope for improvement. For example, the arrangement is relatively complicated, still requires regular monitoring and adjustment and, in practice, may need to be cut out for removal.
The arrangement in Australian Patent Application No. 65583/96 overcomes at least some of disadvantages by providing a spool and wedge drawn together by a bolt, and disengagement means engaging with the wedge to bear against the bolt, forcing separation of the spool and wedge.
The present invention aims to provide an alternative arrangement.